I. Field of the Invention
The present invention relates to an improved anchor bolt assembly.
II. Description of the Prior Art
Anchor bolts have been long employed in building construction to secure static structures or the like to a suitable base, typically poured concrete. These previously known anchor bolts include an anchor end embedded in the concrete and a threaded end which extends upwardly and outwardly from the concrete base. The static structure is positioned over and secured to the threaded end of the anchor bolt by suitable nut members.
These previously known anchor bolts, however, have encountered special difficulties and problems when employed in climates with wide temperature variations, such as might be found in the arctic regions. Under these conditions, the previously known anchor bolts are subjected to relatively large and continuous bending and radial displacement due to cyclic thermal expansion and contraction of the static structure. The cyclic bending of these previously known anchor bolts has resulted in loosening, breakage, fracture and other structural damage to both the anchor bolts and the static structure.
There have been previously known anchor bolt assemblies, such as described in U.S. Pat. No. 3,829,540, in which a sleeve is positioned around the anchor bolt to permit misalignment compensation for the anchor bolt. In this aforementioned patent, the sleeve is constructed from a permanently deformable plastic material. However, this previously known permanently deformable sleeve has not proven successful for cyclic thermal expansion and contraction since the sleeve, once deformed, remains permanently deformed. Consequently, cyclic radial displacement of the anchor bolt due to thermal expansion results not only in the virtually complete deformation of the sleeve, but also in localized stress points on the anchor bolt. These localized stress points on the anchor bolt not only cause a loosening of the anchor bolt but also can even result in fracture and breakage of the anchor bolt at these localized stress points.